IM2_2_Frederiks
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Transcript IM2_2_Frederiks
NYSDOT CORS
Past, Present and
Future
Ron Frederiks
[email protected]
Lots of Acronyms!!!!!!
GPS – Global Positioning System
ABGPS – Airborne Global Positioning System
CORS – Continuously Operating Reference
Stations
NGS – National Geodetic Survey
GIS – Geographic Information System
RTK – Real Time Kinematic Positioning versus
Post Processed Positioning
What is GPS?
Global Positioning System
Satellite-based timing and position
24 satellites (very high orbit)
Developed by U.S. Department of Defense
Considered a Public “Utility”
Signals available free of charge
Satellite Ranging
Measuring the distance from a satellite
Measuring the travel time of radio signals
Signal travels at the speed of light
Trilateration
Ideally, the three spheres will intersect at a discrete
point.
3 seconds out
5 seconds out
7 seconds out
Accuracy of GPS
Depends on several variables
Time
spent on measurements
Design of receiver
Relative positions of satellites
Can be more than 20 meters – autonomous
Sub meter to 5 meters with differential GPS
Sub centimeter with survey products and
differential GPS
Differential Correction
What is it?
Differential
Correction is the process of correcting
GPS data collected by a user, with data recorded
simultaneously at a base station, in order to improve
accuracy.
CORS stations serve as the base stations for
differential correction
Best
results achieved when distance is minimized
between users receiver and the base station.
Dense network of reference stations is desirable.
Differential GPS
Two receivers track the SAME signals and,
therefore, errors at the SAME time
User
Base
Base Stations
Before NYSDOT CORS, we had to rely on
the NGS CORS network
Many gaps in the NGS CORS network
NGS CORS stations collect data at
different rates
NGS CORS stations were not always
reliable
NGS CORS Network
Data Availability (OSPA)
Data Availability (SYCN)
NYSDOT CORS
Conceptualized requirements in 2004
Contract let in Spring 2005
Installation Fall of 2005 thru February 2006
Publishing Static Data to NGS: March 2006
Publishing RTK Corrections Summer/Fall
2006
What is the NYSDOT CORS?
Initially, a Network of 36
Stations Across NYS
Intended Benefits of CORS
Primary Benefit is Publication of Static GPS
Data for Positioning of Project Control
Secondary Benefit is Publication of RTK
Corrections (for Terrain Data Positioning and
Construction Equipment Guidance)
NYSDOT CORS
CORS on 3/30/2006
Data Availability
CORS Station Installations
GPS Receivers Installed on Secure DOT Buildings
Each Antenna Mounted on an 3” Aluminum Mast
Most Masts are Attached to Masonry Load Bearing
Walls
Connected to DOT Statewide (WAN) Network
GPS Data Collection is Totally Automated
Collects & Transmits Data 24/7/365
Automated Network Processing at MO DOT in Albany
Automated Data Backup – In Case of Network Outage
NYSDOT CORS System Will Include Leica Hardware
& Software
CORS Installation
CORS Hardware
Central Statewide Data Management
Network Monitored & Managed by DOT Network
Administrators
Stations Can be Controlled Remotely from Albany
(Set collection rates – view satellites)
Alarm System is Included to Warn of Data Flow
Interruptions
24 Hour Turnaround on Hardware Repairs
UPS Backup Power Source at all Stations
Continuous Monitoring of CORS Network Integrity
to Detect Movement
NGS and Leica also Monitor CORS Network
Integrity
NYDOT CORS
IT Infrastructure
Control Sites/
Log Static Data
Distribute Static Data
Produce Real Time
Data Streams with
Corrections
18 Stations
Distribute Real Time
Data Streams
Distributes Static
Data
RTK Proxy Server
RTK Data distribuiton
18 Stations
Real Time Network Processing
Log .5 sec.
Static data
½ hourly files
Stream 1 sec.
Raw Data for RTK
net processing
Distribute:
•1 sec hourly static RINEX Files to
RTK Proxy Server
•1 sec hourly static RINEX for
internal archive.
•.5 second ½ hourly raw data files
to NGS
•.5 second 12 hour RINEX files to
NYSDOT Photogrammetry
Distribute:
•1 sec hourly RINEX
Static Data
•Single Baseline RTCM
•Nearest Site RTCM
•Single Cell Network
RTCM
•Automatic Cell Network
RTCM
Servers
Site server 24
Network server 25
Site server 45
Publication of Static GPS Data
Automated Publishing of Static Data Files to
National Geodetic Survey (NGS)
Static Data Files will be Available to Public from
NGS – via CORS Website
Static Data will be Published by NGS in RINEX
Format
RINEX Format can be Used by Most GPS
Processing Software
NGS Adjusts National Network, Publishes Positions
for Reference Stations, and Distributes Station
Data For the National Spatial Reference Network
Possibly (in the Future) Incorporate 5 New CORS
Stations Being Installed by NY City
Envisioned Web Delivery
NGS
Spider Web
Publication of Real Time
Kinematic (RTK) Corrections
Automated Publishing of RTK Correction via Internet IP
Address
RTK Corrections can Either be Solved by a Single
Baseline from a CORS Station, or by a Modeled
Network Solution From a Group of CORS Stations
RTK Corrections will be Streamed Out Thru an IP
Address on the Web (User determined data format)
User Accounts Will be Necessary to Access RTK
Corrections
DOT Will Not Charge $ For User Accounts or for Data
Data Can be Accessed by Wireless Phone with Internet
Data Service Plan from a Wireless Provider
Unlimited Number of Users Can Access Data
RTK Clusters
RTK Saratoga test of Cell
Verizon Coverage
Future of NYSDOT Cors
NYSDOT CORS Mission
Ensure Accuracy By:
Network Positions Monitored by NGS & by DOT CORS Software
Station Positions Processed Against National Spatial Reference
Network
Station Positions Reliant on Continuous Network Monitoring, not Single
Station Coordinate
Ensure Reliability By:
Data Interruptions or Station Movements Linked to DOT Alarm System
24 Hr Contracted Maintenance and Hardware Repair
Data Backups Eliminates Data Loss if System Should Go Down
Single Point of Contact and Control of Data Collection Settings
Provide Ease-Of-Use By:
Standardized Non-Proprietary Data Formats
Universally Usable With Most Major Manufacturers
Easily Accessible RTK Data Via Internet
No User Cost Charges for Data
RTK Usable Anywhere Wireless Access is Available
Sample ABGPS CORS Project
Block of photographs near Watertown
ABGPS data used for QA/QC of the aerial
photos
ABGPS data used in Aerotriangulation
adjustment to reduce the amount of
ground control
ABGPS Antenna
Obtaining XYZ Coordinates
ABGPS data post-processed using a base
station near the project area
Used NYSDOT CORS station in
Watertown (NYWT)
Processed with GrafNav software
Specifically
designed for differential correction
of ABGPS data
Plotted in GIS
Fall 2005 Flights in GIS
In Conclusion
NYSDOT Currently has 36 CORS stations
NYSDOT is planning to expand
NYSDOT working with NGS to make NY CORS
part of the National CORS
Data will be made available at no cost
Data will be delivered through web (non RTK)
and registered users (RTK only)
Data delivery to be easy, accurate and reliable
Questions?